The formation of free radicals is a widely accepted pivotal mechanism leading to skin aging. Free radicals are highly reactive molecules with unpaired electrons that can directly damage various cellular membranes, lipids, proteins, RNA and DNA. The damaging effects of these reactive oxygen species are induced internally during normal metabolism and externally through various oxidative stresses. UV exposure and environmental pollution can accelerate skin aging by producing free radicals in skin.
Antioxidants protect cells from the damage of oxidative stress by scavenging free radicals and inhibiting following oxidation reactions. The topical application of antioxidants is broadly used in skin care product to prevent skin aging.
Previously, in cosmetic related fields, polyphenols were reported to show synergistic effects with other antioxidants such as Vitamin E or carotenoids. Also synergistic antioxidant effects were reported based on the combination of carotenoids and tocotrienols.
U.S. Pat. No. 7,452,549, Nestec S. A., discloses a synergistic antioxidant combination of delta tocols and polyphenols. U.S. application publication 2012/0071550, Lycored Ltd., discloses Synergistic combinations of carotenoids and polyphenols. U.S. Pat. No. 5,686,082, L'Oreal, discloses cosmetic or pharmaceutical compositions containing a combination of a polyphenol and a ginkgo extract. U.S. application publication 2003/0206972, J. G. Babish and T. Howell, discloses compositions containing carotenoids and tocotrienols and having synergistic antioxidant effects.
U.S. Pat. No. 7,452,549 measured NO, TNF, PGE2, superoxide inhibition and showed the synergistic effects between delta tocols and polyphenols on suppression of low density lipoprotein oxidation in serum. U.S. application publication 2012/0071550 used UV absorbance and showed synergistic combinations of polyphenols and carotenoids, which can be used to inhibit the production of various inflammatory mediators. None of these patents teach the synergistic effect between phenolic compounds themselves.
In other fields, synergistic antioxidant associations are used to improve the oxidative stability of other chemical in the same systems, such as lubricating oil, biodiesel fuel, and other thermoplastic polymers. U.S. Pat. No. 6,121,209, Exxon, discloses a synergistic antioxidant system. U.S. application publication 2011/0067294, K. Y. S. Ng et al., discloses the effect of natural and synthetic antioxidants on the oxidative stability of biodiesel. U.S. Pat. No. 6,646,035, Clariant Finance (BVI) Limited, discloses synergistic combinations of phenolic antioxidants. U.S. Pat. No. 3,839,210, GAF Corporation, discloses antioxidant compositions comprising a synergistic mixture of a phenol, amice and sulfone.
Combinations of antioxidants are also known in the fields of nutritional supplements, food and beverages. U.S. application publication 2011/0136245, T. L. Parker, discloses synergistic interactions of phenolic compounds found in food. U.S. application publication 2005/0266121, T. C. Lines et al., discloses antioxidative compositions. U.S. application publication 2009/0110674, N. C. Loizou, discloses health supplements. U.S. Pat. No. 6,733,797, W. K. Summers, discloses neuroceuticals for improving memory and cognitive abilities. U.S. application publication 2002/0110604, Ashni Naturaceutical, Inc., discloses compositions exhibiting synergistic antioxidant activity. In these patents, certain phenolic combinations with specific ratios occurring in natural foodstuffs have been reported in U.S. application publication 2011/0136245 only for human nutritional or food preservation; certain phenolic antioxidant combinations have been reported in U.S. Pat. No. 6,646,035 as a stabilizer composition for thermoplastic polymers which are not applicable for cosmetics. None of these patents teach the synergistic effects between phenol/polyphenol compounds that are used in cosmetic formulations.